A method for synthesizing 3-amino-9-phenylcarbazole

Abstract

The invention discloses a method for synthesizing 3-amino-9-phenylcarbazole, and relates to the technical field of photoelectric and dye material chemical synthesis. The method comprises the following steps: adding 9-phenylcarbazole, a reducing agent, tert-butyl nitrite, a catalyst, and a solvent into a reaction container; reacting the mixture until fully reacted at room temperature or under heating conditions after the addition is completed; quenching an organic layer with water, washing the organic layer with water several times, removing the solvent from the organic layer, and performing rapid column chromatography to obtain 3-amino-9-phenylcarbazole. The method uses commercially available 9-phenylcarbazole as a synthesis precursor and tert-butyl nitrite as an amine source; the raw materials are inexpensive, an inert gas atmosphere is not required, and C-N bond construction and reductive primary amination of a nitroso group can be achieved in a one-pot process. The method has the advantages of simple operation, low risk factor, low cost, and C-H bond activation and primary amination conversion at high atom utilization rate. No pre-modification is required, the steps are short, and the three wastes are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of photoelectric and dye material chemical synthesis, in particular to a method for synthesizing 3-amino-9-phenylcarbazole. Background Art

[0002] Carbazole and its derivatives are attracting increasing attention in the field of optoelectronic materials due to their numerous advantages, including their large conjugated system, rigid structure, strong hole transport ability, and stable photochemical properties. Tertiary amines are an important class of monomeric slice structures in optoelectronic materials. Strategies based on the construction of multiple C-N bonds within primary amine slices can efficiently achieve molecular extension and further enhance the photochemical properties of the molecules. 3-Amino-9-phenylcarbazole is a representative naked amine slice, widely used in the synthesis of optoelectronic materials and also plays a key role in the field of dyes. Therefore, the efficient synthesis of 3-amino-9-phenylcarbazole by site-specific amination has been a focus of attention.

[0003] The methods for synthesizing primary amines mainly include the following methods: the first is the classic nitration-reduction amination method, which uses nitric acid as the nitro source to achieve nitration at the potential-rich point, and then uses a reduction system to achieve nitration-amination conversion; the second is the construction of CN bonds under transition metal catalysis, which uses acetamide as the amine source, assisted by transition metals such as Cu or Pd to achieve amine acylation of the bromide, and then hydrolyzes to achieve primary amine conversion; the third is ammonia amination curing, which uses ammonia as the amine source, assisted by Cu catalysis to achieve amination conversion of the halide.

[0004] In the above-mentioned synthetic routes, the classic nitration-amination method requires the use of excessive amounts of mixed acids such as nitric acid, which is highly polluting, has a high risk factor, and produces a large number of three wastes, which is not in line with the essence of green chemistry. In addition, during the reduction process, whether using the classic alkaline sulfide reduction method (problem: sulfur-containing waste residue and sulfur-containing wastewater) or the reduction involving transition metals, it involves hydrazine hydrate (high cost and high toxicity) and hydrogenation reduction (high risk factor and high catalyst cost), further limiting the industrialization process of the reaction. Using acetamide as the amine source requires pre-modification of the aromatic ring. In addition, the process is long and the atom utilization rate is relatively low. The cost of using Pd catalysis is high, while for Cu catalysis, the catalytic temperature is relatively high, which may be unfavorable for subsequent product purification. When using ammonia as the amine source, high temperature and pressure are usually required, which has a high safety factor and also requires pre-modification of the aromatic group.

[0005] In summary, a method for synthesizing 3-amino-9-phenylcarbazole is urgently needed to solve these problems. Summary of the Invention

[0006] The object of the present invention is to provide a method for synthesizing 3-amino-9-phenylcarbazole to solve the problems mentioned in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a method for synthesizing 3-amino-9-phenylcarbazole, comprising adding raw materials, including 9-phenylcarbazole, a reducing agent, tert-butyl nitrite, a catalyst, and an organic solvent, into a reaction vessel, and reacting at room temperature or under heating conditions until sufficient reaction is completed, as shown in the following reaction formula:

[0008]

[0009] The organic layer after the reaction is quenched with water and washed with water several times. The organic layer is freed from the solvent and subjected to flash column chromatography to obtain 3-amino-9-phenylcarbazole.

[0010] Preferably, in the above raw materials, the molar ratio of 9-phenylcarbazole to the reducing agent is 1:(1-2).

[0011] Preferably, the reducing agent is selected from one or more of triethylsilane, polymethylhydrogensilane, and phenylsilane.

[0012] Preferably, the organic solvent is selected from one or more of tetrahydrofuran, ethanol, and ethylene glycol.

[0013] Preferably, the catalyst is selected from one or more of Fe(acac)3, Mn(acac)2, and Co(acac)2.

[0014] Preferably, the above reaction is carried out under air atmosphere.

[0015] Preferably, the heating temperature of the above reaction is not higher than 60°C.

[0016] Preferably, thin layer chromatography (TLC) is used to monitor the reaction process.

[0017] Preferably, the reaction is completed within 10-12 hours.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. This method for synthesizing 3-amino-9-phenylcarbazole does not require high temperature conditions. It uses the commercially available bulk chemical 9-phenylcarbazole as a synthesis precursor and tert-butyl nitrite as an amine source. The raw materials are inexpensive, enhancing the competitiveness of the production process. The reductive amination curing method can achieve the construction of the C-N bond and the reductive primary amination of the nitroso group in a one-pot process. This method is simple to operate, has a low risk factor, and is low in cost. The C-H bond activation primary amination conversion is achieved at a high atom utilization rate without the need for pre-modification, providing new support for the efficient, sustainable, and green development of fine chemicals.

[0020] 2. This method for synthesizing 3-amino-9-phenylcarbazole uses inexpensive, low-toxic Fe salts as catalysts, avoiding the use of expensive and highly toxic Pd catalytic systems and high-temperature, high-pressure Cu catalytic systems, resulting in better operability. The selected ethanol as a solvent is green and environmentally friendly, meeting the requirements of sustainable development. No inert gas protection is required, resulting in stronger operability and better system compatibility. Based on the idea of ​​reduction-catalytic coupling, a targeted primary amination conversion can be achieved without the need for pre-modification, the steps are short, and the three wastes are reduced and the atomic utilization rate is improved.

[0021] 3. The method for synthesizing 3-amino-9-phenylcarbazole uses polymethylhydrogensiloxane (PMHS) or triethylsilane or phenylsilane as a hydrogen source. It is cheap, non-toxic, mild in nature and easy to handle, making it an ideal green reducing agent. DETAILED DESCRIPTION

[0022] The invention discloses a method for synthesizing 3-amino-9-phenylcarbazole. The method comprises the following steps: adding raw materials, including 9-phenylcarbazole, a reducing agent, tert-butyl nitrite, a catalyst, and an organic solvent, into a reaction container, wherein the molar ratio of 9-phenylcarbazole to the reducing agent is preferably controlled to be 1:(1-2); after the addition is completed, the reaction is carried out at room temperature or under heating conditions until the reaction is complete. Thin layer chromatography (TLC) analysis can be used for monitoring during the reaction process. For reference, the reaction usually takes 10-12 hours to complete. If heating is used, the temperature is generally controlled not to exceed 60°C, otherwise the yield is likely to be reduced; and quenching an organic layer with water, washing the organic layer with water several times, removing the solvent from the organic layer, and performing rapid column chromatography to obtain 3-amino-9-phenylcarbazole.

[0023] For reference in the above method, the reducing agent can be selected from one or more of triethylsilane, polymethylhydrosilane, and phenylsilane; the organic solvent can be selected from one or more of tetrahydrofuran, ethanol, and ethylene glycol; and the catalyst can be selected from one or more of Fe(acac)3, Mn(acac)2, and Co(acac)2.

[0024] The reaction of this method can be carried out in an air atmosphere without the need for an inert gas atmosphere, and the steps are relatively simple and easy to control.

[0025] The present invention uses commercially available 9-phenylcarbazole as a basic reaction raw material and tert-butyl nitrite as an amine source to achieve selective naked amination of rich potential sites under a silicon-hydrogen reducing atmosphere. Compared with existing methods, the method does not require the use of expensive transition metal catalysts Pd or high-temperature and high-pressure Cu catalytic systems, has strong and excellent operability, does not require further pre-modification of the substrate, effectively reduces the generation of three wastes, and is more environmentally friendly. In addition, the method uses Fe salts as catalysts, which are low in toxicity and inexpensive, does not require an inert gas atmosphere, has strong operability, uses simple and commercially available substrates, does not require pre-modification, has high atom utilization, and has a short process, providing a new approach for green conversion of direct primary amination.

[0026] The above implementation is further described below through several examples.

[0027] Example 1

[0028] Under air atmosphere, 12.2 g 9-phenylcarbazole (Mr = 243.3, 99%, 0.05 mol), 7.0 g triethylsilane (Mr = 116.28, 99%, 0.06 mol), 1.3 g Mn (acac) 2 (Mr = 253.15, 99%, 0.005 mol) were added to a 250 mL four-necked flask, and 100 mL tetrahydrofuran and 10.3 g tert-butyl nitrite (Mr = 103.12, 99%, 0.1 mol) were slowly added dropwise. After the addition, the mixture was reacted at 60 ° C for 12 h and monitored by thin layer chromatography (TLC). After the reaction, the organic layer was quenched with water and washed twice with water. The organic layer was freed from the solvent and flash column chromatography was performed to obtain 5.64 g 3-amino-9-phenylcarbazole in a yield of 43.7%.

[0029] Example 2

[0030] Under air atmosphere, 12.2 g 9-phenylcarbazole (Mr = 243.3, 99%, 0.05 mol), 5.8 g polymethylsilane (Mr = 115.25, 99%, 0.05 mol), 1.7 g Fe(acac)3 (Mr = 353.17, 99%, 0.005 mol) were added to a 250 mL four-necked flask, and 100 mL ethanol and 10.3 g tert-butyl nitrite (Mr = 103.12, 99%, 0.1 mol) were slowly added dropwise. After the addition, the mixture was reacted at 40 ° C for 10 h and monitored by thin layer chromatography (TLC). After the reaction, the organic layer was quenched with water and washed twice with water. The organic layer was freed from the solvent and flash column chromatography was performed to obtain 11.72 g 3-amino-9-phenylcarbazole in a yield of 90.8%.

[0031] Example 3

[0032] Under air atmosphere, 12.2 g 9-phenylcarbazole (Mr = 243.3, 99%, 0.05 mol), 10.8 g phenylsilane (Mr = 108.21, 99%, 0.1 mol), 1.3 g Co(acac)2 (Mr = 253.15, 99%, 0.005 mol) were added to a 250 mL four-necked flask, and 100 mL ethylene glycol and 10.3 g tert-butyl nitrite (Mr = 103.12, 99%, 0.1 mol) were slowly added dropwise. After the addition, the mixture was reacted at 60 ° C for 12 h and monitored by thin layer chromatography (TLC). After the reaction, the organic layer was quenched with water and washed twice with water. The organic layer was freed from the solvent and flash column chromatography to obtain 7.32 g 3-amino-9-phenylcarbazole in a yield of 56.7%.

[0033] Example 4

[0034] Under air atmosphere, 12.2 g 9-phenylcarbazole (Mr = 243.3, 99%, 0.05 mol), 10.8 g phenylsilane (Mr = 108.21, 99%, 0.1 mol), 1.7 g Fe(acac)3 (Mr = 353.17, 99%, 0.005 mol) were added to a 250 mL four-necked flask, and 100 mL ethylene glycol and 10.3 g tert-butyl nitrite (Mr = 103.12, 99%, 0.1 mol) were slowly added dropwise. After the addition, the mixture was reacted at 40 ° C for 12 h and monitored by thin layer chromatography (TLC). After the reaction, the organic layer was quenched with water and washed twice with water. The organic layer was freed from the solvent and flash column chromatography to obtain 10.27 g 3-amino-9-phenylcarbazole in a yield of 79.6%.

[0035] Example 5

[0036] Under air atmosphere, 12.2 g 9-phenylcarbazole (Mr = 243.3, 99%, 0.05 mol), 5.8 g polymethylsilane (Mr = 115.25, 99%, 0.05 mol), 1.3 g Co(acac)2 (Mr = 253.15, 99%, 0.005 mol) were added to a 250 mL four-necked flask, and 100 mL ethanol and 10.3 g tert-butyl nitrite (Mr = 103.12, 99%, 0.1 mol) were slowly added dropwise. After the addition, the mixture was reacted at 60 ° C for 12 h and monitored by thin layer chromatography (TLC). After the reaction, the organic layer was quenched with water and washed twice with water. The organic layer was freed from the solvent and flash column chromatography was performed to obtain 10.43 g 3-amino-9-phenylcarbazole in a yield of 80.8%.

[0037] Example 6

[0038] Under air atmosphere, 12.2 g 9-phenylcarbazole (Mr = 243.3, 99%, 0.05 mol), 5.8 g polymethylsilane (Mr = 115.25, 99%, 0.05 mol), 1.7 g Fe(acac)3 (Mr = 353.17, 99%, 0.005 mol) were added to a 250 mL four-necked flask, and 100 mL ethanol and 10.3 g tert-butyl nitrite (Mr = 103.12, 99%, 0.1 mol) were slowly added dropwise. After the addition, the reaction was carried out at room temperature for 12 h and monitored by thin layer chromatography (TLC). After the reaction, the organic layer was quenched with water and washed twice with water. The organic layer was freed from the solvent and purified by flash column chromatography to obtain 11.62 g 3-amino-9-phenylcarbazole in a yield of 90.0%.

[0039] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection defined by the claims.

[0040] Any matters not described in detail in the present invention are well-known technologies to those skilled in the art.

Claims

1. A method for synthesizing 3-amino-9-phenylcarbazole, characterized in that: Add raw materials, including 9-phenylcarbazole, a reducing agent, tert-butyl nitrite, a catalyst, and an organic solvent into a reaction vessel, and react at room temperature or under heating conditions until sufficient; quench the organic layer with water, wash it with water several times, remove the solvent from the organic layer, and obtain 3-amino-9-phenylcarbazole after flash column chromatography; The reducing agent is selected from one or more of triethylsilane, polymethylhydrogensilane, and phenylsilane; The catalyst is selected from one or more of Fe(acac)3, Mn(acac)2, and Co(acac)2.

2. A method for synthesizing 3-amino-9-phenylcarbazole according to claim 1, characterized in that: In the raw materials, the molar ratio of 9-phenylcarbazole to the reducing agent is 1:(1-2).

3. A method for synthesizing 3-amino-9-phenylcarbazole according to claim 1, characterized in that: The organic solvent is selected from one or more of tetrahydrofuran, ethanol and ethylene glycol.

4. A method for synthesizing 3-amino-9-phenylcarbazole according to claim 1, characterized in that: The reaction was carried out under air atmosphere.

5. A method for synthesizing 3-amino-9-phenylcarbazole according to claim 1, characterized in that: The heating temperature of the reaction is not higher than 60°C.

6. A method for synthesizing 3-amino-9-phenylcarbazole according to claim 1, characterized in that: The reaction process was monitored by thin layer chromatography.

7. A method for synthesizing 3-amino-9-phenylcarbazole according to claim 6, characterized in that: The reaction takes 10-12 hours to complete.

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